1. Technical Field
The invention relates to structural building blocks, and in particular to a concrete masonry block. Even more particularly, the invention relates to a concrete block having a composition which includes a portion of spent abrasive particles and to the method of making the block.
2. Background Information
Concrete masonry blocks have been used in the building industry for many years and are produced in various sizes, configurations, etc., and are formed from various mixtures of materials. Likewise, there are a variety of manufacturing processes for forming the finished concrete blocks. The blocks have various features, such as a desired or required strength, size, configuration, color, water repellency, etc.
Furthermore, the composition or material makeup of these blocks vary considerably depending upon the desired characteristics to be achieved, such as the price of the finished block, and availability of the materials to be used therein, industry standards, and building codes. One of the main ingredients in these blocks is a filler material which adds strength and bulk to the block and provides various features to the block, such as a binder, color enhancer, etc. These filler materials usually are readily available and are low cost, and in many situations is waste materials, such as fly ash, ground granulated blast furnace slag, and other waste byproducts from manufacturing processes.
Many of these prior concrete or masonry blocks meet the standard industry requirements for water repellant structures. However, this is accomplished by adding costly blends of organic and inorganic materials, such as calcium sterate, ligno sulfates, liquid polymers, surficants, and other ingredients to seal the voids created in the mix design matrix. Inclusion of thermoset particulate media, as set forth in the present invention, accomplishes what these admix chemicals do, but at a lower cost, and a different mechanism.
Another problem with current block manufacturing methods is the removal of excess water from the formed block, usually by applying heat in a drying chamber, such as a kiln or curing room. The ideal situation for the block producer is to have enough water in the mix to completely hydrate the cement in the block in the block forming machine, but not have the block slump upon coming out of the block forming machine. If too much water is contained in the mix, the block will not hold its shape, and cannot be satisfactorily transported without adverse affects to the blocks.
Another problem in forming blocks, especially those desiring a uniform color, is that the wide swings in water content effects the final color of the block.
The various block compositions include various types of filler materials, such as blast furnace slag, fly ash, limestone, sand, gravel, and various lightweight aggregates, which provides the material to which the Portland cement bonds for forming the desired structural block. The particular filler material chosen will effect the cost and structural strength, as well as the water repellency of the finished block. Various types of waste materials, such as fly ash, blast furnace slag, and plastics material, have been used as fillers to provide a use for heretofore useless material.
One type of waste byproduct used as a filler in block manufacturing is various types of plastics. Some examples of concrete block compositions which use various types of plastics as filler material are shown in U.S. Pat. Nos. 4,019,919; 4,058,406; and 4,427,818. Although the blocks of these patents may prove satisfactory for certain applications, it is believed that they may possess certain drawbacks eliminated by the block of the present invention.
In the abrasive blasting art, a considerable quantity of spent abrasive materials, and in particular a thermoset particulate medium, results from blasting procedures. Heretofore, this material had to be placed in a landfill or disposed of in other non-productive manners. Although others in the industry have attempted to incorporate plastic waste products in concrete blocks, the results have not been entirely satisfactory due to the oversizing of the plastic particles used therein.
Therefore, the need exists for an improved concrete block and method of manufacture which uses as one of its filler materials an aggregate polymer, preferably thermoset plastic particles recovered from an abrasive blasting process, to eliminate disposing of such particles in a land fill; and which provides a block which is water repellant, able to be colored, which has increased strength, and which reaches water equilibrium without the addition of water/moisture in a curing chamber.